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    Home > Active Ingredient News > Study of Nervous System > Neurology: Prefrontal cortex blood oxygen level-dependent (BOLD) variability in Parkinson's disease reflects limited environmental adaptability and learned stability

    Neurology: Prefrontal cortex blood oxygen level-dependent (BOLD) variability in Parkinson's disease reflects limited environmental adaptability and learned stability

    • Last Update: 2022-01-23
    • Source: Internet
    • Author: User
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    Growing evidence suggests that the prefrontal cortex (PFC) plays an important role in walking, primarily involved in planning, organization, execution, and adjustment to the environment
    .
    Decreased gait automatism is strongly associated with increased reliance on executive motor control, a form of compensation, with increasing age and disease

    .
    In recent years,
    functional near-infrared spectroscopy (FNIRS) studies of gait have provided direct evidence for this compensation by showing higher mean activation levels of the PFC during normal walking in patients with neurological disorders
    .
    However, in more demanding tasks such as dual-task walking, healthy controls showed elevated mean levels of PFC activation, whereas patients with neurological disorders such as Parkinson's disease (PD) did not

    .
    Limited PFC activation in Parkinson's disease patients is associated with decreased gait ability

    .

    Growing evidence suggests that the prefrontal cortex (PFC) plays an important role in walking, primarily involved in planning, organization, execution, and adjustment to the environment
    .
    Decreased gait automatism is strongly associated with increased reliance on executive motor control, a form of compensation, with increasing age and disease

    .
    In recent years,
    functional near-infrared spectroscopy (FNIRS) studies of gait have provided direct evidence for this compensation by showing higher mean activation levels of the PFC during normal walking in patients with neurological disorders
    .
    However, in more demanding tasks such as dual-task walking, healthy controls showed elevated mean levels of PFC activation, whereas patients with neurological disorders such as Parkinson's disease (PD) did not

    .
    Limited PFC activation in Parkinson's disease patients is associated with decreased gait ability

    .
    Prefrontal cortex (PFC) functional near-infrared spectroscopy (FNIRS)


    FNIRS measurements use light absorption to detect hemodynamic changes in the prefrontal cortex
    .
    FNIRS electrodes placed on the surface of the forehead send and receive light (wavelength 750 to 1000 nm), recording changes in the returned light passing through the skull

    .
    The rationale behind this is that stimulation increases local cerebral blood flow because of higher energy demands in "activated" areas, resulting in higher blood oxygen levels

    .
    Recent reviews, meta-analyses, andconsensusstatements have highlighted the utility of FNIRS in determining changes in hemodynamic response during active walking
    .
    To date, most FNIRS studies have been based on average levels of PFC activity that reflect the average of the FNIRS time series
    .
    However, this approach ignores emerging concepts that suggest that neural activation is an intrinsically variable system that may reveal important insights into brain function

    .
    Recent studies have shown that neuronal variability is an important component of brain function, reflecting development, aging, disease states, task performance, and pharmacological interventions

    .
    These studies argue that temporal signal variability is a measure to quantify the magnitude of moment-to-moment variation in neuroimaging time series

    .
    Two simple forms of this variability are: range, which represents the distribution of data from the lowest value to the highest value in the distribution, and standard deviation (SD), which reflects the overall distribution width of the measurement

    .
    The mean downtrend time series is an additional, slightly more complex form of variability

    .

    FNIRS measurements use light absorption to detect hemodynamic changes in the prefrontal cortex
    .
    FNIRS electrodes placed on the surface of the forehead send and receive light (wavelength 750 to 1000 nm), recording changes in the returned light passing through the skull

    .
    The rationale behind this is that stimulation increases local cerebral blood flow because of higher energy demands in "activated" areas, resulting in higher blood oxygen levels

    .
    FNIRS measurements use light absorption to detect hemodynamic changes in the prefrontal cortex
    .
    FNIRS electrodes placed on the surface of the forehead send and receive light (wavelength 750 to 1000 nm), recording changes in the returned light passing through the skull

    .
    The rationale behind this is that stimulation increases local cerebral blood flow because of higher energy demands in "activated" areas, resulting in higher blood oxygen levels

    .
    FNIRS MeasurementConsensus To date, most FNIRS studies have been based on average levels of PFC activity that reflect the average of the FNIRS time series
    .
    However, this approach ignores emerging concepts that suggest that neural activation is an intrinsically variable system that may reveal important insights into brain function

    .
    Recent studies have shown that neuronal variability is an important component of brain function, reflecting development, aging, disease states, task performance, and pharmacological interventions

    .
    These studies argue that temporal signal variability is a measure to quantify the magnitude of moment-to-moment variation in neuroimaging time series

    .
    Two simple forms of this variability are: range, which represents the distribution of data from the lowest value to the highest value in the distribution, and standard deviation (SD), which reflects the overall distribution width of the measurement

    .
    The mean downtrend time series is an additional, slightly more complex form of variability

    .
    Most FNIRS studies to date have been based on average levels of PFC activity reflecting the average of the FNIRS time series
    .
    However, this approach ignores emerging concepts that suggest that neural activation is an intrinsically variable system that may reveal important insights into brain function

    .
    Recent studies have shown that neuronal variability is an important component of brain function, reflecting development, aging, disease states, task performance, and pharmacological interventions

    .
    These studies argue that temporal signal variability is a measure to quantify the magnitude of moment-to-moment variation in neuroimaging time series

    .
    Two simple forms of this variability are: range, which represents the distribution of data from the lowest value to the highest value in the distribution, and standard deviation (SD), which reflects the overall distribution width of the measurement

    .
    The mean downtrend time series is an additional, slightly more complex form of variability

    .


    Functional magnetic resonance imaging studies have shown that with age, blood oxygen level-dependent (BOLD) variability decreases in cortical regions, whereas BOLD variability increases in subcortical regions such as the striatum
    .
    In addition, BOLD variability measures showed greater ability to predict age than central propensity measures such as mean, and healthy controls exhibited less variability in the task compared to younger populations, suggesting that these Important information contained in the indicator

    .
    Furthermore, participants who performed better on cognitive tasks exhibited higher variability in brain signals, suggesting that variability in neural processing may actually be beneficial, potentially reflecting flexibility

    .
    The study also showed that BOLD variability increases from rest to task and is related to task difficulty
    .
    This further suggests that variability in brain signaling plays an important role in the nervous system's ability to adapt to changing environments or, in some cases, to remain stable

    .
    Most of these aspects of adaptability and flexibility have been reported in the context of prefrontal neural networks, which exhibit different variability in different behavioral situations requiring flexibility or stability

    .
    In exercises that include task repetition, low variability is required to adapt and maintain specific task goals, while flexibility to switch to different tasks requires high variability

    .
    Therefore, stable and flexible behavior is essential for successful walking in everyday life

    .

    Functional magnetic resonance imaging studies have shown that with age, blood oxygen level-dependent (BOLD) variability decreases in cortical regions, whereas BOLD variability increases in subcortical regions such as the striatum
    .
    In addition, BOLD variability measures showed greater ability to predict age than central propensity measures such as mean, and healthy controls exhibited less variability in the task compared to younger populations, suggesting that these Important information contained in the indicator

    .
    Furthermore, participants who performed better on cognitive tasks exhibited higher variability in brain signals, suggesting that variability in neural processing may actually be beneficial, potentially reflecting flexibility

    .
    Blood Oxygen Level Dependence (BOLD)


    A recent study demonstrated changes in within-individual PFC variability during daily walking and dual-task walking in older adults using FNIRS

    .
    Standard deviations (SDs) of FNIRS-derived oxyhemoglobin (HBO2) measurements were calculated for each walking task and compared between participants with altered task and cognitive abilities

    .
    Variability was increased in the dual-task walking condition compared to the simpler walking condition

    .
    In addition, older adults with cognitive impairment experienced greater increased variability across tasks compared with those without cognitive impairment

    .
    Studies of walking while dual-tasking in Parkinson's disease patients have shown that dual-tasking increases variability in walking performance with a strong negative effect

    .
    However, the HBO2 variability of FNIRS in Parkinson's disease patients has not been evaluated

    .
    Parkinson's disease is a neurodegenerative disease with marked gait and cognitive deficits

    .


    Recently, some researchers assessed the effect of task difficulty on HBO2 variability by comparing ordinary walking and dual-task walking, and by comparing the difference between task repetitions to assess the effect of task practice on HBO2 variability to study and healthy controls.
    To compare, investigate different aspects of intra-individual HBO2 variability during walking in patients with Parkinson's disease

    .
    The comparison between regular walking and dual-task walking allowed the examination of neural flexibility, while the comparison between task repetitions allowed the examination of neural stability
    .

    Recently, some researchers assessed the effect of task difficulty on HBO2 variability by comparing ordinary walking and dual-task walking, and by comparing the difference between task repetitions to assess the effect of task practice on HBO2 variability to study and healthy controls.
    To compare, investigate different aspects of intra-individual HBO2 variability during walking in patients with Parkinson's disease

    .


    A total of 206 subjects, 57 healthy controls (age: 68.
    9 ± 1.
    0 years, 27 women) and 149 patients with idiopathic Parkinson's disease (age: 69.
    8 ± 0.
    6 years, 50 women) were included in the study, course: 8.
    27±5.
    51 years) with conventional walking and dual-task walking (3 consecutive subtractions) with FNIRS system placed on the forehead

    .
    HBO2 variability was calculated using the standard deviation (SD), range and mean detrended time series of FNIRS-obtained HBO2 signals assessed in each walking task

    .
    HBO2 variability between groups and between different walking tasks was compared using mixed model analysis

    .

    • Variability (SD, range, mean detrended time series) during dual-task walking was higher than usual walking (P<0.
      025), but this was due to differences within healthy controls (Group X task interaction: P<0.
      007)

      .
    • In healthy controls, task repetition showed decreased variability, while in Parkinson's disease patients, variability was increased (interaction group*walk-repetition: P<0.
      048)

      .
    • All subjects' MDSUPDRS motor scores were positively correlated with HBO2 range (r=0.
      142, p=0.
      050) and HBO2 SD (r=0.
      173, p=0.
      018) during normal walking

      .
  • Variability (SD, range, mean detrended time series) during dual-task walking was higher than usual walking (P<0.
    025), but this was due to differences within healthy controls (Group X task interaction: P<0.
    007)

    .
  • In healthy controls, task repetition showed decreased variability, while in Parkinson's disease patients, variability was increased (interaction group*walk-repetition: P<0.
    048)

    .
  • All subjects' MDSUPDRS motor scores were positively correlated with HBO2 range (r=0.
    142, p=0.
    050) and HBO2 SD (r=0.
    173, p=0.
    018) during normal walking

    .

  • This study proposes a new approach to explain changes in HBO2 variability, linking increased HBO2 variability with flexible adaptation to environmental challenges and decreased HBO2 variability with stability in performance
    .
    The results suggest that both concepts are limited in PD, but these concepts require further research

    .
    In addition, the HBO2 variability measure, an important aspect of brain function, provides new insights into the role of the PFC in aging and walking in Parkinson's disease

    .

    This study proposes a new approach to explain changes in HBO2 variability, linking increased HBO2 variability with flexible adaptation to environmental challenges and decreased HBO2 variability with stability in performance
    .
    The results suggest that both concepts are limited in PD, but these concepts require further research

    .
    In addition, the HBO2 variability measure, an important aspect of brain function, provides new insights into the role of the PFC in aging and walking in Parkinson's disease

    .


    This study provides class III evidence that patients with Parkinson's disease have more variability in Hb02 signaling during normal walking compared to healthy controls, but not during dual-task walking

    .

    Source: Maidan I, Hacham R, Galperin I, Giladi N, Holtzer R, Hausdorff JM, Mirelman A.
    Neural Variability in the Prefrontal Cortex as a Reflection of Neural Flexibility and Stability in Patients With Parkinson Disease.
    Neurology.
    2021 Dec 14: 10.
    1212/WNL.
    0000000000013217.
    doi: 10.
    1212/WNL.
    0000000000013217.
    Epub ahead of print.
    PMID: 34906983.

    Maidan I, Hacham R, Galperin I, Giladi N, Holtzer R, Hausdorff JM, Mirelman A.
    Neural Variability in the Prefrontal Cortex as a Reflection of Neural Flexibility and Stability in Patients With Parkinson Disease.
    Neurology.
    2021 Dec 14:10.
    1212/WNL .
    0000000000013217.
    doi: 10.
    1212/WNL.
    0000000000013217.
    Epub ahead of print.
    PMID: 34906983.


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